It will never work and your marriage will never recover with him in the picture. They are not friends, they are lovers. No Contact is the only way it will work. You, as the betrayed spouse, can NEVER regain trust as long as there any contact. Here is what Harley says about it:
"My experience helping couples recover from infidelity has taught me that any contact between the unfaithful spouse and the lover ruins reconciliation. Even casual contact prevents completion of withdrawal from the addiction of an affair. Since an affair is usually an addiction, the only way to fully recover is to permanently separate the unfaithful spouse (the addict) from the lover (the source of the addiction). But even in the very few cases when an affair is not an addiction, total separation of the spouse and lover is a necessary act of consideration for the feelings of the betrayed spouse. It's the very least a wayward spouse can do to compensate for the suffering caused by the affair. Continued contact with a lover simply perpetuates the suffering of the betrayed spouse indefinitely.
It's been my experience that without total separation, mutual love cannot be restored, resentment cannot be overcome and protection from the threat of another affair cannot be guaranteed. So when I counsel couples who want to reconcile after an affair, I insist on total separation of the unfaithful spouse and the lover with extraordinary precautions to guarantee that they never see or talk to each other again."
comtinued at:
http://www.marriagebuilders.com/graphic/mbi8113_ab.html